205666101 has 8 divisors (see below), whose sum is σ = 304690560. Its totient is φ = 137110716.

The previous prime is 205666079. The next prime is 205666103. The reversal of 205666101 is 101666502.

It is a happy number.

It is not a de Polignac number, because 205666101 - 2⁷ = 205665973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 7617263 = 205666101 / (2 + 0 + 5 + 6 + 6 + 6 + 1 + 0 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205666103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3808605 + ... + 3808658.

It is an arithmetic number, because the mean of its divisors is an integer number (38086320).

Almost surely, 2^205666101 is an apocalyptic number.

It is an amenable number.

205666101 is a deficient number, since it is larger than the sum of its proper divisors (99024459).

205666101 is an equidigital number, since it uses as much as digits as its factorization.

205666101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7617272 (or 7617266 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 205666101 is about 14341.0634542910. The cubic root of 205666101 is about 590.2747939515.

The spelling of 205666101 in words is "two hundred five million, six hundred sixty-six thousand, one hundred one".